Bicycle brake

A bicycle brake is a device used to reduce speed or prevent a bicycle from moving. These systems work by using friction to manage energy. When a rider applies the brakes, the system converts the kinetic energy of the bike and rider into thermal energy, which is heat. This heat is then dissipated into the surrounding air.

Most modern systems consist of three essential components. The first is the mechanism for the rider to apply the signal, such as brake levers or pedals. The second is a transmission mechanism, like Bowden cables, hydraulic hoses, or rods, which carries the signal to the wheel. The third is the brake mechanism itself, such as a caliper or a drum, which presses surfaces together to create friction.

The history of braking is as old as the bicycle itself. In 1817, Karl Drais included a pivoting brake shoe that pressed against a rear iron tyre. Early bicycles like the "boneshaker" used a spoon brake, which was a pad pressed onto the rear wheel. This was often operated by a lever or a cord connected to the handlebars. Penny-farthings also relied on spoon brakes or the technique of back pedalling to slow down. As bicycle designs evolved between 1870 and 1878, braking moved toward the front wheel. John Kean introduced a front brake in 1873. By 1880, front brakes were widely adopted because they offered much greater stopping power.

As technology changed, new braking methods were required to protect new materials. The introduction of pneumatic tyres by the Dunlop Tyre Company created a problem for spoon brakes. These brakes tended to wear through the thin casing of pneumatic tyres very quickly. To solve this, Abram W. Duck patented the Duck Roller Brake on November 23, 1897. This system used a rod and a lever to pull twin rubber or wood rollers against the front tyre.

In 1898, the first internal coaster brakes were introduced for the rear wheel. These were contained within the rear wheel hub and were controlled by backpedaling. Because the braking happened inside the hub, it eliminated the issue of tyre wear. Coaster brakes became very common in the United States throughout the first half of the 20th century.

Rim brakes are a very common type of braking system used today. They are called rim brakes because the braking force is applied by friction pads to the rim of the rotating wheel. These pads can be made of materials like rubber, cork, or leather and are often mounted in metal shoes.

Rim brakes offer several advantages, including being inexpensive, lightweight, and mechanically simple. They are also easy to maintain and provide powerful stopping force. However, they have specific disadvantages. They perform poorly when the rims are wet and can brake unevenly if the rims are warped. Additionally, rim brakes are prone to clogging with mud or snow because the rims carry debris from the ground directly to the pads.

Maintaining rim brakes is vital for rider safety. The brake pads will naturally wear down over time and must be replaced. As they wear, their position may need adjustment to keep them centered.

If the rims themselves become too worn, they can fail catastrophically. It is also important to watch for heat build-up. During a long descent on a heavily laden bike, the friction can generate thermal energy faster than it can dissipate. This heat build-up can potentially damage components or cause brake failure. Some riders use ceramic coatings on rims to reduce wear and improve heat insulation.

Different materials can be used to change how a brake performs. Brake pads come in many shapes and materials to suit different needs. A softer rubber pad can provide more braking force with less effort, while a harder pad lasts longer.

For wet-weather riding, some cyclists use special pads containing iron (iii) oxide. These salmon-colored pads, produced by companies like Kool-Stop, provide higher friction on wet aluminum rims than standard rubber. For carbon fiber rims, riders must be careful to use non-abrasive cork pads to avoid damaging the material.

Modern cycling has also seen the rise of disc brakes, which offer different benefits than rim brakes. While rim brakes act on the wheel's outer edge, disc brakes use a metal rotor.

This design allows the braking surfaces to stay higher off the ground, making them less likely to clog with mud. Because the braking happens on a dedicated disc, these systems often perform more consistently in various weather conditions. Whether using a simple rim brake or a complex hydraulic disc system, the goal remains the same: the safe and controlled management of motion through friction.